Process for winding synthetic yarn

ABSTRACT

The present invention is to provide an improved yarn winding process in a drawtwister for drawing, twisting and packaging synthetic yarn, particularly a yarn winding process when the drawtwister is brought to a standstill. When a package is completed and the drawtwister is to be stopped, a ring is moved to the uppermost end of a bobbin with a full package to wind irregular yarn occuring while the machine is being stopped. In this state the machine is temporarily stopped and thereafter rerun for a short time to lower the ring to a waste spool at the base of the spindle to wind the irregular yarn on the waste spool and the machine is completely stopped.

United States Patent Nakanishi et a1.

1 Sept. 17, 1974 PROCESS FOR WINDING SYNTHETIC YARN Inventors: HajimeNakanishi; Kohei Kawashima, both of Matsuyama, Japan Assignee: TeijinLimited, Osaka, Japan Filed: Nov. 6, 1972 Appl. No.: 303,871

US. Cl. 57/156, 57/34 T'T, 242/18 EW Int. Cl D0lh 9/02, B65h 54/86 Fieldof Search 57/34 TI, 34 PW, 36, 156;

- 242/18 EW, 18 PW References Cited UNITED STATES PATENTS l/1927 Colman242/18 EW 1/1963 Lohest et a1. 57/34 TT 12/1967 Johnson et a1 242/18 EWX Primary Examiner.lohn W. Huckert Assistant Examiner-Charles GorensteinAttorney, Agent, or Firm-Sherman & Shalloway [5 ABSTRACT waste spool atthe base of the spindle to wind the irregular yarn on the waste spooland the machine is completely stopped.

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B C D A0 80 amwam 29.5mm 0233mm O, mjozim m0 SE m PATENTEU 1 74 SHEET 70F 7 1 PROCESS FOR WINDING SYNTHETIC YARN The present invention relatesto improvements in a winding process in which yarn is wound with adrawtwister, and particularly to improvements in a winding process whenthe drawtwister is being stopped.

In drawing synthetic yarn such as polyamides and polyesters, the undrawnyarn unwound from an undrawn yarn package is drawn, twisted and wound ina package on a bobbin inserted into a wind-up spindle in a drawtwister.This drawing and packaging operation is simultaneously carried out onall the spindles of the drawtwister and when desired packages on eachbobbin are completed, the machine is stopped to remove all the fullpackages from the machine and insert new empty bobbins for a seconddrawing and packaging operation.

Since the amount of yarn on one undrawn yarn package corresponds to thatof four to five drawn yarn packages, drawing and packaging operationsare continuously carried out with four to five consecutive operations ifone undrawn yarn package is threaded on the drawtwister, andconsequently, the drawtwister is started up and stopped four to fivetimes.

An undrawn yarn on an old package and an undrawn yarn on a new packageare tied with each other before the undrawn yarn on the old packagebecomes empty, and the undrawn yarn is provided to enable continuousdrawn yam packaging.

However, as described above, when one drawn yarn package becomes full,the drawtwister should be stopped to replace an empty bobbin for thefull bobbin 1 and restarted.

The synthetic yarn drawn at the start-up of the drawtwister before themachine reaches normal speed is different from the yarn drawn at normalspeed in yarn qualities and should be prevented from being included inthe regular yarn package. For this reason, a traverse ring is maintainedin the position of a waste spool secured at the base of the spindle atthe start-up of the machine to wind up initial irregular yarn thereon.After the machine has reached normal speed, the ring is traversed alonga bobbin situated above the waste spool to form a regular yarn packageon the bobbin.

On the other hand, when the package is completed on the bobbin and thedrawtwister is to be stopped, the machine runs by inertia for some timeafter the turning off of its drive motor to stop, during which themachine runs at speed lower than normal speed and the resulting drawnyarn should be prevented from being included in a regular yarn packageat the start-up of the machine. Hence, at the stoppage of the machine,the ring is lowered in a waste spool position, and irregular yam duringthe rotation by momentum .is wound on the waste spool aftermotors fordriving the machine are switched off.

Since the ring is situated in the waste spool position at the beginningof a winding operation and returns to the position at the end of theoperation; two yarns bridge the waste spool and the bobbin. Inreplacement of bobbins, a full bobbin can be removed from the spindlewithout interfering with the yarn threaded on the machine when the twoyarns are severed. Accordingly after the removal of a full bobbin, asubsequent winding operation can be started only with the insertion ofthe empty bobbin into a spindle.

When in such a way one winding operation is completed, the machine isstopped without severing the yarn threaded on the machine and thereaftera full bobbin is replaced by an empty bobbin. Without rethreading themachine with yarn, the machine can immediately be started for asubsequent winding operation. This is called continuous simultaneousdoffing.

Recently drawing and packaging speed in a drawtwister has becomeexceedingly high to increase production and at the time of start up ofthe machine, the time required for reaching normal speed takes longer.In like manner, after the switching-off of the machine, the time .ofrotation by inertia up to a complete stoppage takes longer; in otherwords, the time required for deceleration has become longenWhen theamount of windings on a package becomes greater and the weight ofpackage is heavier, momentum of the spindle assembly holding a packagebecomes greater, and consequently, inertial rotating time is furtherlengthened. Accordingly, the amount of irregular yarn to be wound on thewaste spool at the times of starting and stopping of the machine becomesexceedingly great.

However, if the amount of irregular yarn to be wound on a waste spoolincreases, the above-described continuous simultaneous doffing becomesactually impossible. When each waste spool becomes full, it may bereplaced by an empty spool or the waste on the spool may be severed. Inthis case, since the yarn wound on the waste spool is severed,continuous simultaneous doffing is inevitably suspended. Threading eachspindle of the machine with yarn is newly carried out and irregular yarnduring the threading is wound on the waste spool. When the threading iscompleted throughout the machine, the ring is lifted to a bobbinposition. Therefore, if the amount of irregular yarn at the start andstoppage of the machine becomes greater as described above, this is anextreme case but the waste spool happens to be full with only onewinding operation and continuous winding operations become impossible.

On the other hand, a wound-up package is unwound and undergoes varioustreatments in subsequent treatment processes. In this case, yarn isdrawn off over the end of the package. Thus a terminal winding of thewound yarn, that is, a leading thread end of yarn is preferably locatedat the top of the package. In order to attain the two objects ofminimizing the amount of waste yarn to be wound on the waste spoolduring one winding operation and positioning the initial thread end ofthe yarn at the upper end of the package, it has been proposed that thering is lifted to the upper end of a bobbin where the bulk of a packageis not held at the mechanical stoppage of the drawtwister to lead andwind an initial thread end of the package there and spin the most partof irregular yarn caused during the inertial rotation of the machine onthe uppermost end of the bobbin, and then the ring is lowered to a wastespool position below the bobbin.

However, though in this process, the amount of irregular yarn to bewound on the waste spool becomes less, a great amount of irregular yarnis wound on the surface of the package during this lowering movement ofthe ring to a waste spool position, and after the removal of the packagefrom the machine, it should be stripped off from the package. Thisstripping off operation which is much complicated and requires a lot ofhand labor leaves much room for improvement. Further in this process,the proper timing of the ring lowering movement from the top of a bobbinto the position of the waste spool is very difficult. If thecommencement of descent of the ring is too early, the machine is stillrotating at considerably high speed when the ring has reached the wastespool position, resulting in that the waste yarn wound on the wastespool becomes more. In contrast, if the commencement of descent of thering is too late, troubles will arise that the machine stops before thering reaches the waste spool; that is, during this lowering movement,the machine stops to cause yarn breakage. Further even if the machinedoes not stop before the ring reaches the waste spool position, anothertrouble occurs that yarn is broken to prevent a normal winding operationwhen the machine has been started unless it is fully wound on the wastespool.

In packaging, a transfer tail is, in general, formed at the base of abobbin. The transfer tail is formed on the lower end of the bobbin wherepackage of yarn is not formed by the yarn layer initially wound on theinnermost layer of package, that is, on the surface of the bobbin. Whenat the completion of a wind operation, the ring descends to the wastespool position and irregular yarn is laid on the transfer tail at thebase of the bobbin. This transfer tail becomes frayed or sloughed offwhen the irregular yarn thereon is stripped off from the bobbin, andbecomes impossible to use as a transfer tail.

In a conventional drawtwister, the drawing section where yarn is drawn,and a spindle of the ring twisting and packaging section where thedrawing yarn is twisted and packaged have so far been driven by a commondrive source. The drawing, and the twisting and packaging sections havebeen started and stopped at the same time. However, drawing speed hasrecently become higher and the weight of a yarn package has beenincreased. This renders difficult the driving of the drawing section andthe twisting and packaging section with one and the same motor. Further,it is arranged that revolutions per minute of a spindle holding a yarnpackage is gradually decreased as the package is near full to lessen theload on the motor at the time of completion of packaging and prevent theincrease of packaging tension of the yarn. For this reason, a moderndrawtwister is provided with individual motors for use in driving thedrawing section, and the twisting and packaging section or the spindlesection independently of each other. The present invention provides animproved yarn winding process in such a drawtwister having individualdrive means.

SUMMARY OF INVENTION In the present invention, when a drawtwister havingindividual drive sources for the drawing and packaging sections is setin stoppage, a ring is raised to the upper most end of a bobbin forwinding irregular yarn thereon to be generated a time when the machineis being stopped. The machine is temporarily stopped as it is.

Afterwards only the drawing section of the machine is rerun at low speedand the ring is lowered to a waste spool position below a bobbin. Whenthe ring has descended to that position, the spindle as well is rerun atlow speed and the irregular yarn is wound on the waste spool. Then, thedrawing section and the spindle are completely stopped. Thus a terminalend of yarn of a package is led to the uppermost end of the bobbin andthe amount of irregular yarn to be wound on the waste spool is minimizedto cause as many continuous simuitaneous doffings as possible. At thesame time, irregular yarn is prevented from wrapping itself around thesurface of the full package of regular yarn during the lowering movementof the ring to facilitate the stripping-off of irregular yarn, and atransfer tail is prevented from the entanglement.

According to the present invention, the drawing section is rerun, withan auxiliary, low speed drive source instead of the normal drive sourcefor the drawing section and the timing of ring descending speed inreference to a drawing speed is easily adjusted to prevent yarnbreakage.

Further objects and advantages of the present invention will becomereadily apparent as the following detailed description of the inventionunfolds when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of outlinedmechanism of one embodiment of a drawtwister of the present invention.

FIG. 2 is a fragmental side elevation of traversing mechanism of a ringrail of the drawtwister in FIG. 1.

FIG. 3 is a detail side elevation of a twisting and packaging section ofthe drawtwister.

FIG. 4 is a detail view of the waste spool of FIG. 3.

FIG. 5 is speed diagrams of each section of the drawtwister at thestoppage thereof for describing the process of the present invention inthe drawtwister of FIG. 1.

FIGS. 6, 7 and 8 are graphs showing the relation of lowering oftreatment speed with qualities of treated yarn: Tensile strength of yarnin FIG. 6, shrinkage of yarn in boiling water in FIG. 7, and dyeabilityof yarn in FIG. 8.

FIG. 9 is speed diagrams of each section of a drawtwister when themachine is set in stoppage for explaining another embodiment of thepresent invention.

FIG. 10 like FIG. 9 is a speed diagram in stili another embodiment ofthe present invention.

FIG. 1 I is a sectional view of a package wound by the process as shownin FIG. 10.

For the drawing and packaging sections, only one drawing and packagingunit is shown for simplicity in a driving system. Ordinarily onedrawtwister is provided with about to drawing and twisting units andthese are simultaneously driven by driving source.

In FIG. 1, undrawn yarn unwound from an undrawn yarn package 1 isreceived with a feed roller 3 bearing on a nip roller 2 and drawn toseveral times the original length between the feed roller 3 and a drawroller 4 having a peripheral speed higher than that of the feed roller3. In drawing, heat treatment may be carried out whenever necessary withappropriate heating means FIG. 1, multi-step drawing is carried out witha plurality of draw rollers in some cases. The yarn thus drawn passesthrough a lappet guide 5 and a traveler 7 mounted on a ring 6 andsliding thereon. Then the yarn is wound on a bobbin 9 mounted on arevolving spindle 8 to form package 10.

Driving mechanism of the drawing section comprising the feed roller 3and the draw roller 4 will be described below.

The feed roller 3 is directly arranged on a rotary shaft 11longitudinally extending along a drawtwister and at one end of therotary shaft 11 is provided a gear 12. On the otherhand, to the rotaryshaft 13 of the draw roller 4 is attached a helical gear 14, whichmeshes with a he lical gear 15 intersecting it at right angles. Thehelical gear 15 is secured to a driving shaft 16 longitudinallyextending along the drawtwister. A gear 17 is connected to one end ofthe driving shaft 16 and to the gear 17 is connected to one end of thedriving shaft 16 and to the gear 17 is connected a gear 12 through agear train 18. The feed roller 3 and the draw roller 4 rotate ininterlocking arrangement and the speed ratio, that is draw ratio, isdetermined by the size of each gear and the diameter of each roller. Apulley 20 is mounted on a shaft 19 of the gear 17 and is connected to apulley 23 secured to an output shaft 22 of a motor 21 through a belt 24.The rotation of the driving motor 21 for driving the drawing section istransmitted by the aid of such transmission gears to the feed and drawrullers constituting the drawing section.

The driving of a spindle at the twisting and packaging section will bedescribed below. A tin pulley 29 is mounted on a tin pulley shaft 28longitudinally arranged along the drawtwister. A spindle belt isextended between the pulley 8a of the spindle 8 and the tin pulley 29through idle pulleys 31, 32, and the spindle 8 is driven by friction incontact with the spindle belt 30 through the pulley 8a. A motor 26 fordriving the spindle is direct-coupled with an end of the tinpulley shaft28 through a coupling 27, and is generally variable in speed.

The traversing motions of the ring 6 reciprocating up and down along thebobbin 9 will be described below.

A ring holder 33 holding in place the ring 6 is secured to a ring rail34 extending along the length of the draw twister and makes up-and-downmotions with those of the ring rail 34. One end of a suspension belt 35is attached to the ring rail 34 and the other end thereof to a pulley36. Another pulley 38 is secured to a rotary shaft 37 of the pulley 36and to the pulley 38 is attached one end of a belt 39. The other end ofthe belt 39 is attached to a traverse bar 40 reciprocating left andright (see FIG. 2). The end of the traverse bar 40 is connected to apiston rod 43 of a cylinder 42 through a coupling 41. Pressure oil isalternately fed to both sides of the piston rod 43 of the cylinder 42 topermit the piston rod 43 to make a reciprocating motion and the pulley38 to make a reciprocal turn by the aid of the traverse bar 40. Thepulley 36 arranged coaxially with the pulley 38 is also causedto make areciprocal turn to reciprocate ring rail 34 through the suspension belt35. The stroke of the piston rod 43 is amplified according to the ratioof diameter of the pulley 38 to that of the pulley 36 and transmitted tothe ring rail 34. The

ring traversing mechanism is driven and controlled independently of thedrawing section and the spindle.

A lower-speed auxiliary driving source at the drawing section will bedescribed below. A lower-speed auxiliary drive motor 45 is connected tothe end of an output shaft 22 of a motor 21 by the aid of anelectromagnetic clutch 44. The motor 45 is variable in speed, forinstance, with the use of a pole change type. In normal driving, theelectromagnetic clutch 44 is off and the drawing section is driven withthe motor 21. However, after the temporary stoppage of the drawtwisterand at its restart, the electromagnetic clutch 44 is actuated during thering lowering movement to connect the output shaft 22 with the motor 45such, that the motor 45 restarts the drawing section at lower speed.

The winding process in sucha drawtwister in the present invention isdescribed below.

At the start of drawtwisting, the ring rail 34 is positioned in thelowest position to hold the ring 6 to the position of a waste spool 46mounted on the spindle 8 at the base of the bobbin 9. The state of thepackaging section is shown in FIG. 3. In this case one drawtwistingoperation has already been carried out and yarn Y is threaded on thedrawing section and kept wound on a waste spool 25 via a traveler 7 (Atthe initial start of drawtwisting, a threading-up operation is required,but in this instance the threading-up operation can be omitted becauseof the continuous simultaneous doffing operation described before).After the full package is re placed by an empty bobbin, the motors 21and 26 are turned on at this state to start the drawtwister and the ring6 is held in the position of the waste spool 25 until the feed roller,the draw roller and the spindle resume normal speed. Afterwards the ring6 is traversed along the bobbin 9 to form a package 10. During theascending movement of the ring 6 from the position of the waste spool 25to the position of the bobbin 9, a transfer tail d is formed at the baseof the bobbin as shown in FIG. 4. In FIG. 4, the traversing motions formpackage of yarn by what is called a parallel winding process in whichtraverse length gradually lessens. To decrease gradually traverselength, the stroke of the hydraulic cylinder 42 reciprocating up anddown the ring rail 34 is shortened by controlling the change-over timingof pressure oil fed to the hydraulic cylinder.

In this way, the desired package 10 is completed on the bobbin 9, andthereafter the ring 6 is lifted to the upper end of the bobbin 9immediately before or simultaneously with the turning-off of the motors21 and 26 of the drawtwister. This state is shown by the two-dot chainline in FIG. 3. The drawtwister is temporarily stopped in that state andirregular yarn generated during the inertial rotation of the machine iswound on the uppermost end of the bobbin as a bunch of yarn a. Theirregular yarn produced after the mechanical stop of the machine hasbeen reached and before the spindle is brought to a complete standstillis all wound on the uppermost end of the bobbin. Then the ring 6 is lowered to the waste spool position for the start of a subsequent windingoperation. The electromagnetic clutch 44 is actuated to start only thedrawing section (feed and draw rollers) and drive it at an exceedinglylow speed with the lower speed auxiliary drive motor 45 while theprimary motor 21 is kept suspended and the ring 6 is lowered to theposition of the waste spool 25 with preventing yarn b from wrappingitself around the package. In order that the ring 6 may be lowered, the

rate of flow of pressure oil to be fed to the hydraulic cylinder 42 isincreased by the control of a flow control valve (not shown). Generally,this ring lowering speed becomes about several times as high as anordinary ring traversing speed. When the ring 6 has lowered, the polenumber of the motor 45 is reduced to increased speed in the drawingsection and the motor 26 for driving the spindle is also started at lowspeed and to 20 windings are laid on the waste spool 25. Thereafter themotors 45 and 26 are turned off to bring the machine to a completestandstill.

FIG. 5 shows speed diagrams at the stoppage of members of a draw twisterin conducting such a winding process. In the diagrams, drawing sectionspeed (draw roller speed), rpm of the spindle and ring traverse (ringposition) are plotted as ordinate and periods of time as abscissa. Thediagrams just illustrate the time relations of start and stoppage of thedrawing section, the spindle and the ring traverse. The ordinate doesnot show the accurate size of the actual speed nor does the abscissashow actual time intervals.

Referring to FIG. 5, the winding process as embodied will be described.When the package 10 is completed on the bobbin 9 (a time A), the ring 6is lifted to the upper end of the bobbin (point H) and the motors 21 and26 are turned off. Since the drawing section and the spindle areseparately driven with individual motors, it'is difficult to synchronizethe stoppage of the spindle and that of the drawing section. After theswitch off, the drawing section and the spindle rotate by inertia,gradually decelerate and come to a complete standstill (from the time Ato a time B0 or a time B). However, the drawing section is widelydistinguished from the spindle in inertia. Ordinarily, the inertia ofthe spindle holding a considerably heavier package becomes greater.Hence, when both motors 21 and 26 are simultaneously turned off, thespindle continues to rotate for a long period of time after the stoppageof the drawing section.

The stoppage of both motors is preferably simultaneous. If the spindlecontinues to rotate for a long period of time after the stoppage of thedrawing section yarn is twisted off. For this reason, a brake isactuated on the spindle motor to stop the spindle in as short a time aspossible. In FIG. 5, the motors 21 and 26 are supposed to be turned offsimultaneously at the time A for convenience sake, but the motor 26 isturned off a little earlier than the motor 21 to have their time ofstoppage agree with each other. In stopping the drawtwister, the drawingsection is stopped at the time B0 and the spindle a little later at thetime B by applying a brake or staggering a time for turning off eachmotor to adjust their stoppage timing and prevent yarn from beingtwisted off.

The ring is held in a position H until the spindle is brought into acomplete stoppage at the time B to wind the irregular yarn at theuppermost end of the bobbin.

Afterwards, only the drawing section is driven at lower speed for ashort time with the auxiliary motor 45 and the ring is lowered from theupper end (the position H) of the bobbin to the waste spool (positionI). When the ring has completed its descent to the waste spool position(position I) (a time C), the pole number of the motor 45 is reduced toincrease speed in the drawing section and the spindle motor 26 isstarted at low speed while the ring is being held in the position.

The spindle motor 26, which is variable in speed, is capable of beingstarted at low speed and there is no need to use an auxiliary motor forlow-speed driving. Even if the rpm of the spindle at the time of restartat a lower speed is somewhat greater, it does not interfere withpackaging through the rpm of a traveler becomes greater.

The drawing section stops when a time D comes and the spindle stops alittle later at a time Do to stop the drawtwister completely. Since itis still difficult to stop the drawing section and the spindle at thesame time, the driving periods of time and speed of the motors 45 and 26are controlled such that the spindle stops :1 little later than thedrawing section.

The irregular yarn produced during the internal rotation of the machinefrom A to the time B0 is wound on the uppermost end of the bobbin as thebunch of yarn a in FIG. 4, but since as described above during the ringlowering movement (from B to the time C), the spindle is not inrotation, the irregular yarn will not wrap itself around the package. Inthe prior art, the spindle has so far been rotated during the ringlowering movement and the irregular yarn has been allowed to wrap itselfon the surface of a package as shown by the one-dot chain line e in FIG.3.

After the time C when the descent of the ring to the position of thewaste spool is completed, the spindle is driven at low speed, andconsequently the desired amount of yarn (5 to 20 windings of yarn) iswound on the waste spool so as to give a satisfactory start-up for asubsequent winding operation without any yarn breakage.

At the machine downtime, doffing and donning are carried out by severingthe portion of yarn c extending from the waste spool 25 to the transfertail section (FIG. 4), removing the package 10, and mounting an emptybobbin on the spindle 8 to complete one winding operation.

As irregular yarn does not wrap itself around the surface of the packagewound by the process of the present invention, the removal of theirregular yarn from the surface of the package becomes unnecessary andonly the bunch a of irregular yarn at the uppermost end of the bobbinhas only to be stripped. Thus the stripping operation becomes verysimple.

Further, because yarn is not laid on the transfer tail d formed at thebase of a bobbin (FIG. 4) at the completion of a winding operation theentanglement and the being frayed of the transfer tail can beeliminated.

The leading thread end of a package is led to the upper end of thebobbin after the completion of the package by the shifting of a ring tothe upper end of a bobbin, and thereby the handling of the package in asubsequent process becomes convenient.

During the ring lowering movement, the drawing section is driven at alower speed and yarn is fed with ring lowering speed, resulting in noyarn breakage at the time. Further, at the beginning of a subsequentdrawtwisting, yarn wound accurately on a waste spool will not cause yarnbreakage at the start of the machine.

Further the amount of irregular yarn to be wound on the upper-most endof a bobbin depends on the length of time from A to the time B; that is,the longer the time of inertial rotation at the drawing section, themore is the amount of irregular yarn (waste yarn). It is preferable thatthe time is as short as possible. After turning off the motor 21, it isdesirable to apply the brake to the motor 21 or the driving system ofthe drawing section and minimize the period of time of the inertialrotation.

As described above, in the present invention no irregular yarn is woundon the surface of packageand only the stripping off the bunch a (FIG. 3)of irregular yarn at the uppermost end of the bobbin is-required.

In the conventional methods, about 170 to 200 meters of irregular yarnhas so far been wound on one bobbin, but in the present invention it haswidely been decreased to 10 meters. As a result, about only 1 minute isnow required to strip off 80 packages compared with 7 minutes in theconventional methods. The number of operators required for treating10,000 packages/day have been reduced. That is, the reduction of sixoperators has become possible.

As described above, yarn to be discarded as irregular yarn has beenreduced and it contributes much to cost reduction.

As described before, the time as abscissa in FIG. does not denote anactual time. The actual time at the stoppage of the drawing section andthe spindle in the process of FIG. 5 will be described below.

In a drawtwister having 140 to 150 units, drawing is conducted at aspeed of 1,000 to 1,300 m/min and a package weighing 2.5 to 3.0 kg iscompleted by a spindle varying from 15,000 to 7,000 rpm.

First, after the turning off of the motor, the drawing section stops in15 to 25 sec (A to the time B) and the spindle stops to sec behind thestoppage of the drawing section. In the spindle section, inertia isgreat and the brake is usually applied to the motor to adjust the timerequired for complete stoppage. Accordingly, between A and the time B is25 to 40 sec in FIG. 5. The time required for the ring lowering movementbetween B and the time C is 3 to 5 sec, during which time the drawingsection is driven at low speed at a peripheral speed of the draw rollerof about 2 to about 7.5 m/min. When the ring reaches the position of thewaste spool, the peripheral speed of the draw roller is raised to 8 to24 m/min, preferably about 15 m/min as shown in FIG. 5 C D in windingyarn on the waste spool. A time C D requires about see. In this way, lowdriving speed is changed over in two steps to eliminate yarn breakageduring the ring lowering movement and wind yarn accurately on the wastespool after the completion of ring descent. As a result, a time B D forlow speed driving in the drawing section is about sec. Five to 10seconds after the stoppage of the drawing section,

to the uppermost end of the bobbin was conducted just before or at thesame as the turning off of the driving motor in the drawtwister. Thatis, in the process in FIG. 5, the ring was lifted at a time A.

However, it has been found that in drawing synthetic yarn, yarn drawn ata lower speed than usualis not substantially different from the yarndrawn at normal speed in yarn properties. Hence, the yarn drawn duringthe inertial rotation after the turning off of the motors .drawn yarnproduced under normal conditions until drawing speed lowers to a certainextent and that it can be used as regular yarn. This will be describedin more detail below.

In general, itis said that in yarn treatment such as drawtwisting, etc.,yarn properties change with decrease in treatment speed (drawing speed).However, changes in yarn properties do not appear a time when decreasein drawing speed has started, that is, a time when the driving motor hasbeen turned off but often appear a time when the drawingspeed has widelybeen decreased. Accordingly the yarn treated during the time from theturning off of each driving motor to the substantial appearance ofchanges in yarn properties can be inserted to a package without anytrouble and wound as the package instead of being discarded as irregularyarn, waste. Substantial changes in yarn properties in reference to thedecrease of treatment speed depend upon types of yarn and treatmentprocess, and consequently they should be empirically determined fromtreatment process to treatment process.

According to experiments of the inventors, for instance, when undrawnpolyethylene terephthalate yarn having an intrinsic viscosity of 0.65was drawn at C (drawing temperature), C (heating temperature), 3.7 times(draw ratio) and 1,000 m/min (drawing speed) into 75-denier, 48-f1lamentdrawn yarn, tensile strength, shrinkage in boiling water and dyeabilityin reference to each yarn speed were measured after the turning off ofdriving motors for the machine. The results are shown in FIGS. 6, 7 and8.

Dyeability here means a grade of a disperse dye affinity for yarn.Assuming that the dyeability of yarn drawn at a drawing speed of 1,000m/min is zero whether the yarn dyes heavier or lighter is measured by asensory test stands for heavier dyeing and stands for lighter dyeing).

Shrinkage in boiling water is a percentage of the contracted length of ayarn specimen having a given length to the original length after theyarn specimen has been dipped in boiling water a few minutes. FIG. 6shows that the yarn has little or no different properties from regularyarn until the drawing speed declines to 500 m/min. I

In view of this point, there is no need to lift a ring rapidly until thetime A when each driving motor of the machine has been turned off astaught by the winding process in FIG. 5, but the ring may be lifteduntil a time Ao when after the turning off of driving motors, the speedof the drawing section is on the verge of reaching the limit speed Vo asin FIG. 9.

The winding process as in FIG. 9 is identical with that .in FIG. 5except the timing of ring lifting. In this way,

the ring is lifted to the upper end of the bobbin until drawing speedhas reached the limit speed V0 after the turning off of the machine tomake easy stripping operation of the irregular yarn and to save theamount of yarn to be discarded as waste which is economical.

When a package wound in a drawtwister is subsequently used, a leadingend of the package is desired to be easily located and drawn. For thispurpose, at the stoppage of the machine, the ring is led to the outerside (upper end) of a package and temporarily stopped there to wind abunch of regular yarn. Thus the leading portion of yarncan be securedthereon.

Such a winding process will be described with reference to FIGS. and 11.The winding process in FIG. 10 is almost the same as that of FIG. 9except a slight difference in ring traversing. FIG. 1 l is a crosssectional view of a package wound by the process of FIG. 10.

In FIG. 10, when a package becomes full, the motors for driving thedrawing section and the spindle are first turned off at a time A. Justbefore the time A0 when the speed of the drawing section has reached thelimit speed V0, the ring is lifted to position Ho and temporarilystopped there. The position H0 is located outside (upper end) the bulkof the package and below the position H where a bunch of irregular yarnis wound. Thus immediately after a bunch of regular yarn a, is formed inthe position Ho if the bobbin, the ring is lifted in the time A0 to forma bunch of irregular yarn a in the position H. Then the ring is rapidlylowered to the waste spool position. The process after the formation ofa bunch of irregular yarn in the position H is identical with that ofFIG. 5.

The periods of time during which ring traversing is temporarily stoppedin the position Ho are sufficient enough to obtain the number ofwindings required for securing the end of yarn to the bobbin andordinarily about 0.2 to 3 sec will be enough. The bunch of yarn a shouldbe formed outside the bulk of the package, that is, the upper end of.the bobbin. The bunch can be formed on the belly of the package, butinduces disad vantageously stains, fuzzing and sloughing off of thepackage. The bunch a, for securing a leading end of bin mounted on thetwist spindle, and irregular yarn occurring at the starting and stoppingof the drawtwister is wound on the irregular yarn winding section, whichcomprises switching off each of said motors when winding of the yarn onthe bobbin is completed, then moving the ring to the uppermost end ofthe bobbin to wind the bunch of irregular yarn, formed during theinertial rotation before the drawtwister is brought to a completestandstill, restarting only the drawing section at low speed after thecompletion of the standstill of the drawtwister, lowering the ring tothe irregular yarn winding section, then restarting the spindle at lowspeed to wind the irregular yarn on the irregular yarn winding section,and thereafter stopping the drawing section and the spindle.

2. A process for winding synthetic yarn as set forth in claim 1 whereinthe low speed restart of the drawing section is carried out with anauxiliary drive motor other than the primary driving motor.

3. A process for winding synthetic yarn as set forth in claim 1 whereinafter the ring has been lowered to the irregular winding sectionposition, speed in the drawing section is rendered higher than that atthe time of the lowering movement of the ring and the spindle isrestarted at low speed.

4. The process of claim 1 wherein after the driving motors of thedrawtwister are turned off, the ring is regularly traversed to theuppermost end of the bobbin to wind the irregular yarn occurring uponthe stopping of the drawtwister.

5. The process of claim 4 wherein after the driving motors of thedrawtwister are turned off, the ring is temporarily stopped on the upperend of the bobbin before the formation of the irregular yarn bunch towind regular yarn on the upper end of the bobbin, and the ring is thenfurther moved upward to the uppermost portion of the bobbin to wind theirregular yarn.

1. A process for winding synthetic yarn in a drawtwister in which adrawing section and a twist spindle are driven individually withseparate motors, a ring is reciprocated up and down along the twistspindle, an irregular yarn winding section is arranged below a bobbinmounted on the twist spindle, and irregular yarn occurring at thestarting and stopping of the drawtwister is wound on the irregular yarnwinding section, which comprises switching off each of said motors whenwinding of the yarn on the bobbin is completed, then moving the ring tothe uppermost end of the bobbin to wind the bunch of irregular yarn,formed during the inertial rotation before the drawtwister is brought toa complete standstill, restarting only the drawing section at low speedafter the completion of the standstill of the drawtwister, lowering thering to the irregular yarn winding section, then restarting the spindleat low speed to wind the irregular yarn on the irregular yarn windingsection, and thereafter stopping the drawing section and the spindle. 2.A process for winding synthetic yarn as set forth in claim 1 wherein thelow speed restart of the drawing section is carried out with anauxiliary drive motor other than the primary driving motor.
 3. A processfor winding synthetic yarn as set forth in claim 1 wherein after thering has been lowered to the irregular winding section position, speedin the drawing section is rendered higher than that at the time of thelowering movement of the ring and the spindle is restarted at low speed.4. The process of claim 1 wherein after the driving motors of thedrawtwister are turned off, the ring is regularly traversed to theuppermost end of the bobbin to wind the irregular yarn occurring uponthe stopping of the drawtwister.
 5. The process of claim 4 wherein afterthe driving motors of the drawtwister are turned off, the ring istemporarily stopped on the upper end of the bobbin before the formationof the irregular yarn bunch to wind regular yarn on the upper end of thebobbin, and the ring is then further moved upward to the uppermostportion of the bobbin to wind the irregular yarn.